Ectodermal embryogenesis contributes to development of the epidermis and associated structures such as sweat glands, sebaceous glands, mammary glands, Meibomian glands, hair follicles and nails. Ectoderm derivatives also include the anterior ⅔ of the oral cavity, and structures including the epithelia of salivary glands, the enamel of teeth, the covering of the tongue, and part of the pituitary gland.
X-linked hypohidrotic ectodermal dysplasia (XLHED) is a rare X chromosome-linked genetic disorder. It is the most common of the ectodermal dysplasias, a spectrum of more than 170 genetic disorders that are characterized by at least one primary morphological defect of ectodermal structures (Pinheiro, M. et al., Am J Med Genet. 1994 Nov. 1; 53(2):153-62, the contents of which are incorporated herein by reference in its entirety). XLHED is clinically characterized by fine, sparse hair (hypotrichosis); few and often pointed teeth (marked oligodontia); diminished or absent eccrine function (hypohidrosis) associated with an elevated risk for life-threatening hyperthermia; and a predisposition to serious, clinically-significant respiratory infections associated with reduced secretory gland function. In addition to humans, the disease has been identified in dogs, mice and cattle.
XLHED is caused by mutations in the EDA gene, chromosomal locus XqI2.q13.1 (Kere, J. et al., Nat Genet. 1996 August; 13(4):409-16). The EDA gene encodes several splice variants, the longest of which encodes the 391 aa. protein EDA-A1 that is a member of the TNF family and binds specifically to its cognate receptor EDAR. Replacement studies in mice and dogs have confirmed that EDA-A1 is the only EDA gene product necessary to activate the EDA/EDAR signaling pathway (Casal, M. L. et al., Am J Hum Genet. 2007 November; 81(5):1050-6; Gaide, O. et al., Nat Med. 2003 May; 9(5):614-8).
The EDA-Al/EDAR pair signals through an adaptor molecule called the ectodysplasin-A receptor associated death domain (EDARADD) and the transcription factor nuclear factor-kappa B (NF-κB) pathway (Elomaa, O. et al., Hum Mol Genet. 2001 Apr. 15; 10(9):953-62; Headon, D. J. et al., Nature. 2001 Dec. 20-27; 414(6866):913-6; Kumar, A. et al., J Biol Chem. 2001 Jan. 26; 276(4):2668-77; Schmidt-Ullrich R, Tobin D J, Lenhard D, Schneider P, Paus R, Scheiderheit C (2006), Development 133: 1045-1057). The interaction of EDA-A1 and EDAR exerts a regulatory role that is tightly associated with epithelial-mesenchymal interactions and pathways that regulate ectodermal appendage formation and organogenesis in the embryo (Laurikkala, J. et al., Dev Biol. 2001 Jan. 15; 229(2):443-55).
Therefore the genotypic incapacity to synthesize functional EDA-A1 protein results in an XLHED phenotype due to defective ectodermal development. EDA-A1 has been shown to be involved in the morphogenesis of hair follicles and tooth buds during early development.
In this disorder, there is significant morbidity and mortality in affected children due to hyperthermia, caused by the inability to sweat. Significant morbidities include increased risk of respiratory tract infections, ocular disease due to dry eyes, as well as difficulties with mastication, growth retardation, poor appearance, and speech impairment resulting from tooth abnormalities (delayed dentition, conical tooth crowns (peg-shaped teeth) and oligodontia). As XLHED is an X chromosome-linked genetic disorder, the clinical phenotype is consistently severe in affected males and more variable in heterozygous females as the result of random X chromosome inactivation.
The first model of XLHED was identified in mice selected from the Black 6 strain for large size which resulted in the spontaneous appearance of a sub-strain with abnormal hair and tooth development. The affected animals (designated “Tabby mice” due to the resemblance of the fur patterning of the heterozygote females to that of the tabby cat) lack functional EDA protein due to a frame-shift mutation resulting in the absence of the domain necessary for receptor binding and signaling that is critical for normal tooth, hair and sweat gland morphogenesis (Ferguson, B. M. et al., Hum Mol Genet. 1997 September; 6(9):1589-94; Srivastava, A. K. et al., Proc Natl Acad Sci USA. 1997 Nov. 25; 94(24):13069-74). Consequently, these mice have no sweat glands and no hair on the tail. The Tabby mouse currently is a widely used model for XLHED.
There is a dog model of the disease that has been used in XLHED studies. A German shepherd puppy was identified with a phenotype similar to human XLHED (Casal, M. L. et al., Mamm Genome. 2005 July; 16(7):524-31), and the effect was later bred into the Beagle strain, which is more commonly used for laboratory experimentation. Beagles carrying the EDA mutation exhibit a phenotype equivalent in many significant respects to that of humans. Advantages of the canine model include high geno-/pheno-copy and a dose similarity to human developmental maturation at birth, while disadvantages include the minimal transplacental immunoglobulin transport.
Given the severity of the phenotypic manifestations of XLHED including hyperthermia and respiratory tract infections in the first years of life, followed by significant and life-long health and quality of life issues, there remains a long-felt need for treatment interventions at every stage of life. To date, there is no satisfactory treatment that has been approved for patients affected by XLHED.
Until recently, correction, alteration and/or mitigation of the phenotypic presentations associated with XLHED in animal models has been accomplished by the administration of a recombinant form of the ligand for the EDA receptor. Such recombinant compositions previously identified include those described in detail in U.S. patent application Ser. No. 12/756,268 filed Apr. 8, 2010 which is a continuation of U.S. patent application Ser. No. 10/503,999 filed Oct. 25, 2004, now granted U.S. Pat. No. 7,736,657, which is a 35 U.S.C. Section 371 National Phase Entry Application of International Application No. PCT/EP2002/009354 filed Aug. 21, 2002, which designates the U.S., and which claims the benefit of priority of German Application No. 10205368.5 filed Feb. 10, 2002 and German Application No. 10205583.1 filed Feb. 11, 2002, the contents of which are each incorporated herein by reference in their entireties.
Administration to the fetus of such recombinant compositions has, until now, been effected only via administration to the mother via an intravenous route. Such studies are disclosed in co-pending and commonly owned International Application PCT/US2012/037251 filed May 10, 2012, the contents of which are incorporated herein by reference in their entirety. In Tabby mice prenatal EDA1 replacement via maternal injection of EDI200 corrected the developmental abnormalities to a far greater extent than postnatal administration to newborn pups.
This approach, however, may not be optimal for achieving therapeutic levels of corrective protein in a human fetus and additionally exposes the mother to high serum levels of the exogenous molecule. The inventors hypothesize that direct injection of EDI200 into the amniotic fluid could result in fetal uptake, possibly via gut and lung, leading to a prolonged drug exposure at levels sufficient for successful treatment of XLHED.
The present invention provides compositions and methods for the correction and/or reversal of ectodermal dysplasia, in particular XLHED, phenotypes through direct intra-amniotic administration of recombinant amino-acid based compounds and compositions which comprise EDI200 monomers, multimers, variants, fragments and/or combinations of the foregoing.